Radio frequency technology is used in a variety of applications, two broad categories of which are sensing and communication. The former category includes such diverse applications as Magnetic Resonance Imaging (MRI) and Radio Detection and Ranging (Radar). The latter category includes wireless communication using a myriad of different frequency bands and protocols including cellular telephony. Cellular telephony has revolutionized communication and continues to grow in importance. For cellular telephony in particular distinct frequency bands are often used in the same geographic area because there are competing standards and in order to support legacy devices. Moreover, more frequency bands are being allocated for higher bandwidth services that are being introduced. A particular wireless device may support more than one protocol for more than one application. Examples of protocols are, RFID, WLAN, WiMAX, UWB, 3G and 4G. Examples of applications are multimedia, mobile internet, connected home solutions, and sensor-networks. In this situation it is desirable to provide increasing physical channel diversity (e.g., frequencies, polarizations) in a single wireless communication device. Diversity can also be a means to improved Quality of Service (QoS) in challenging Radio Frequency (RF) environments (e.g., urban settings). Moreover, reconfigurable, multimode antennas are needed to be able to adapt to multiple user positions, restrictive data mode grips, and other environmental variables. As a result, there is a strong demand for antennas that are resonant at multiple frequencies or can be tuned to multiple frequencies and/or different polarizations and that have thin and flexible form factors. Consumer expectations call for small wireless handsets (e.g., cellular telephones, smart phones, etc.), which have limited space for their antenna systems. Thus, there is a strong need for antenna systems that provide more frequency bands and agile polarization diversity without requiring much more space.
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